EP2791528B1 - Twin clutch with wear compensation device in particulary for an automotive vehicule - Google Patents

Description

The present invention relates to a dual clutch catch-up wear, especially for a motor vehicle.

A double clutch alternately couples the motor shaft of the vehicle with two coaxial input shafts of a gearbox, which can be robotic type.

Thus, a dual clutch allows to change gears while maintaining the transmission of a torque engine to the vehicle wheels. Indeed, the two clutches are respectively associated with even and odd gear ratios. During a gearshift, a first clutch is disengaged while the second clutch is engaged, so that the engine torque is progressively transferred from the first to the second clutch.

Each clutch comprises a mechanism comprising a diaphragm for cooperating with a pressure plate integral in rotation with the cover and the motor shaft. Each diaphragm is movable by means of a corresponding clutch abutment, between a rest position and an active position. Depending on the type of clutch, the active position of the diaphragm corresponds to a coupling or decoupling of the shafts of the engine and the gearbox and the rest position of the diaphragm corresponds to a decoupling or a coupling of these shafts. These are respectively a normally open clutch and a normally closed clutch.

The clutch stop is controlled by an actuator controlled by an electronic computer to exert a predetermined force on the diaphragm and move it over a given distance.

The pressure plate of each clutch, biased by the corresponding diaphragm, is intended to clamp a friction disc on a corresponding reaction plate. A reaction plate can be provided for each clutch. Alternatively, a single reaction plate common to both clutches, mounted between the two friction discs, is used.

Each friction disk is rotatably connected to an input shaft of the gearbox and each reaction plate is rotatably connected to a flywheel connected to the drive shaft. Thus, the clamping of a friction disk between the corresponding pressure and reaction plates allows the transmission of a torque between the drive shaft and the shaft of the associated gearbox.

The use of the clutches causes wear of the friction linings of the friction discs as well as the counter-materials of the associated pressure and reaction plates. This results in a variation of the position of each pressure plate with respect to the reaction plate, generating a variation of the clamping force of the friction disk and a modification of the position of the licking point and the abutment. clutch. It is recalled that the licking point is the position from which a portion of the engine torque is transmitted to the gearbox shaft when closing the clutch.

The document FR 2 847 626 , in the name of the Applicant, proposes a clutch equipped with wear compensating means interposed between a pressure plate and a diaphragm mounted on a cover attached to a reaction plate. These wear-compensating means comprise a ring with circumferential ramps which cooperate with counter-ramps complementary to the pressure plate. The ramp ring also serves to support the diaphragm so that the rotation of the ring relative to the pressure plate causes the ramps to move relative to the counter-ramps and thus the axial displacement of the pressure plate. relative to the diaphragm, lid and reaction plate. The distance between the pressure plate and the associated reaction plate is thus varied in a way that offsets the wear.

A toothed member is also fixed on the ramp ring and meshes with a worm mounted in a cassette attached to the cover, the toothed member being at right of the worm.

The worm is coupled in rotation with a ratchet wheel cooperating with a pawl fixed on the cover. The worm and / or the ratchet wheel are axially pressed by an elastic member against a wing of the cassette.

The pawl is in the form of an elastic blade having a control tab cooperating with the teeth of the ratchet wheel so as to allow the rotation of the ratchet wheel in a direction of rotation, in case of wear, and to prevent the rotation of the ratchet wheel in the opposite direction of rotation, the first diaphragm bearing against a pawl of the return tongue, so as to move the control tab during its actuation.

In this way, in case of wear and during successive actuations of the diaphragm, the pawl causes rotation of the ratchet wheel and the worm, the latter causing rotation of the ring carrying the ramps, by the intermediate of the toothed organ. This progressively increases the distance between the pressure plate and the cover and gradually decreases the distance between the pressure plate and the associated reaction plate, so as to compensate for wear.

The patent application FR 2 860 845 discloses the use of such wear compensating means in a double clutch. First and second wear compensating means are associated with a first and a second clutch mechanism. The wear compensating means are each arranged in the vicinity of the associated pressure plate. Their axial positioning between the different parts of the clutches, inside the cover, however, results in a large axial and radial space.

The document US 7,080,722 discloses a dual clutch equipped with wear catching means located near each of the trays pressure, the wear compensating means however using another type of technology. The document WO 03/029675 discloses yet another variant of a double clutch equipped with means of catching wear. These solutions also have the disadvantages described above.

The invention aims in particular to provide a simple, effective and economical solution to this problem.

For this purpose, it proposes a dual clutch catch-up wear, especially for a motor vehicle, comprising at least one reaction plate intended to be coupled in rotation to a drive shaft, a first and a second friction disc bearing trims of friction, for coupling respectively to first and second driven shafts, first and second pressure plates, respectively actuated by a first and a second diaphragm so as to each clamp or release a friction disc between the pressure plate and the corresponding reaction plate, the first pressure plate being fixedly connected to a cover movable in translation relative to the reaction plate and being actuated by pressing the first diaphragm on the movable cover, and means of catching up the wear of the first friction disk, the first pressure plate and / or the associated reaction plate, characterized in that the The wear compensating means comprise ramp means, arranged on the side of the first diaphragm, cooperating with counter-ramp means, arranged on the side of the movable cover, the ramp means and the counter-ramp means being arranged between the first and the second diaphragm. diaphragm and the movable cover so that the rotation of the ramp means relative to the counter-ramp means changes the distance between the first diaphragm and the movable cover, the ramp means having a toothing meshing with a worm, the wear compensating means further comprising means for driving the worm in rotation, able to be made operational by wear when the first diaphragm is actuated, the worm being carried by a part integral with the worm; reaction plate cooperating with the first pressure plate for clamping the first friction disk.

The wear compensating means which function similarly to those of the document FR 2 847 626 , are no longer disposed between a diaphragm and the associated pressure plate, but between the first diaphragm and a movable cover connected to the first pressure plate. They can thus be located away from the first pressure plate, in an area less subject to space constraints.

In operation and in case of wear, the movable cover deviates from the first diaphragm so as to compensate for this wear. The axial position of the first diaphragm is not modified by wear. Consequently, the axial position of the ramp means carrying the toothing, bearing against the first diaphragm, is also not modified. As a result, the position of the toothing relative to the worm is independent of wear, which ensures the proper operation of the wear compensating means.

According to the invention, only the first clutch mechanism is equipped with wear compensating means. Indeed, this first clutch mechanism is generally intended to drive the shaft associated with the odd speeds reports, in particular the first gear ratio. The first friction disk, the first pressure plate and the associated reaction plate thus undergo greater wear than the others. The fact of dispensing with wear-compensating means in the second clutch mechanism further limits the axial and radial overall dimensions of the assembly.

According to one characteristic of the invention, the double clutch comprises a single reaction plate, arranged axially between the first and second friction discs.

Preferably, the driving means of the worm comprise a ratchet wheel integral in rotation with the worm, cooperating with a pawl adapted to be displaced during the actuation of the first diaphragm.

In addition, the second pressure plate, the second friction disk and the second diaphragm can be housed in a lid attached to the corresponding reaction plate, the worm being rotatably mounted in a cassette attached to the lid, at the same time. outside of it.

The worm and / or the ratchet wheel can be rotatably mounted inside the cassette, the worm and / or the ratchet wheel being pressed by an elastic member against a closed face of the cassette.

The hardened, hardened face is more resistant to wear due to the friction of the worm and / or the ratchet wheel, which makes it possible to have a constant friction torque over time and to avoid fretting and / or micro-welding phenomena.

According to another characteristic of the invention, the first diaphragm comprises an external peripheral finger for actuating the pawl, the cover carrying a bearing washer of the second diaphragm having an opening allowing the passage of said actuating finger, when the actuation of the first diaphragm.

Such a design makes it possible to further increase the compactness of the assembly while avoiding any interaction between the second diaphragm and the support washer.

Advantageously, a toothed member meshing with the worm is fixed on the ramp means, the bending or the axial displacement of the toothed member being limited by two opposite stops.

This ensures the proper positioning of the toothed member vis-à-vis the worm and, therefore, the reliability of wear compensating means.

In particular, the bending or the axial displacement of the toothed member may be limited by a rim of the cassette, on the one hand, and by the means for fixing the cassette on the lid, on the other hand.

According to yet another characteristic of the invention, the first diaphragm is pivotally mounted on the lid by means of rivets, the tilting of the first diaphragm being limited, in one direction, by the heads of said rivets and, in the other direction , by a substantially radial face of the movable cover.

The heads of the rivets serving as a stop for the first diaphragm may have a general T-shape whose lateral branches are intended to bear against radially internal fingers of the first diaphragm.

Such a shape makes it possible in particular to limit the radial size of the heads of the rivets.

In addition, the ramp means may comprise a ring mounted in rotation and in translation around a cylindrical portion of the movable cover, the ring having circumferential ramps which cooperate with complementary counterbands formed on the movable cover.

Preferably, the pawl is in the form of an elastic blade having a control tab cooperating with the teeth of the ratchet wheel so as to allow the rotation of the ratchet wheel in a direction of rotation in case of wear, and preventing the rotation of the ratchet wheel in the opposite direction of rotation, the first diaphragm bearing against a pawl return tab, so as to move the control tab when actuating the first diaphragm.

In addition, the pawl may comprise at least one lateral lug forming an abutment intended to abut against the lid during the actuation of the first diaphragm.

• la figure 1 est une demi-vue en coupe axiale d'un double embrayage selon l'invention,
• la figure 2 est une vue en perspective d'une partie du double embrayage,
• les figures 3 à 5 sont des vues de détail et en perspective, illustrant les moyens de rattrapage d'usure du double embrayage selon -l'invention,
• la figure 6 est une vue en perspective et en coupe axiale d'une partie du double embrayage,
• les figures 7 et 8 sont des vues de détail, en perspective et de côté, de deux variantes illustrant notamment le maintien en position de l'organe denté,
• la figure 9 est une vue écorchée et en perspective d'une partie du double embrayage,
• la figure 10 est une vue de détail, en perspective, illustrant l'ouverture ménagée dans la rondelle d'appui du second embrayage,
• les figures 11 et 12 sont des vues de détail, en perspective, illustrant le positionnement des rivets de centrage du premier diaphragme sur le couvercle,
• la figure 13 est une vue en perspective d'une partie du double embrayage selon l'invention.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example with reference to the accompanying drawings in which:

• the figure 1 is a half-view in axial section of a double clutch according to the invention,
• the figure 2 is a perspective view of a part of the double clutch,
• the Figures 3 to 5 are detailed and perspective views, illustrating the means of compensating for wear of the double clutch according to the invention,
• the figure 6 is a perspective view in axial section of a part of the double clutch,
• the Figures 7 and 8 are detailed views, in perspective and from the side, of two variants illustrating in particular the holding in position of the toothed member,
• the figure 9 is a broken and perspective view of a part of the double clutch,
• the figure 10 is a detail view, in perspective, illustrating the opening formed in the bearing washer of the second clutch,
• the figures 11 and 12 are detailed views, in perspective, illustrating the positioning of the centering rivets of the first diaphragm on the cover,
• the figure 13 is a perspective view of a part of the double clutch according to the invention.

The figures 1 and 2 illustrate a double clutch according to the invention, for coupling a motor with a first and a second input shaft 1, 2 of a gearbox. The double clutch comprises first and second clutches 3, 4 of different ratios of parities.

The first clutch comprises a first pressure plate 5 and a reaction plate 6 between which a first friction disc 7 extends. The first pressure plate 5 is coupled in rotation to the reaction plate 6 and is movable in translation relative to to it, between an engaged position and a disengaged position, in which it squeezes the first friction disc 7 on the reaction plate 6, or respectively releases the first friction disc 7.

The reaction plate 6 is fixed on a cover 8 coupled to the motor shaft. The first friction disc 7 is coupled to the first input shaft 1 of the gearbox. Thus, in the engaged position of the first clutch 3, the motor shaft is coupled to the first input shaft 1 of the gearbox.

The first pressure plate 5 is fixed on a cover 9 movable in translation relative to the reaction plate 6 and the cover 8, and extending towards the front.

A first diaphragm 10 is pivotally mounted on the cover 8, by means of rivets 11 ensuring the centering of said diaphragm 10 while allowing it to tilt. The first diaphragm 10 is in the form of an elastic annular plate bearing on the cover 8 at a bearing zone 12, the first diaphragm pivoting around this bearing zone 12. The bearing zone 12 is formed by a projecting portion of the cover 8.

The control of the first clutch 10 is conventionally performed by means of a first clutch abutment 13 cooperating with the radially inner periphery of the first diaphragm 10. The first diaphragm 10 forms a lever transmitting the force applied by the first control stop 13 to the first pressure plate 5, via the movable cover 9.

In order to allow effective clamping of the first friction disc 7, the first diaphragm 10 is pre-loaded at rest. Without this pre-charge, the diaphragm 10 would, at rest, in a state of elasticity requiring a start of travel of the relatively large control stop 13 to apply an effective clamping force on the corresponding friction disk 7. When the first clutch release 13 is actuated, it balances the pre-charge of the first diaphragm 10 before starting the clamping of the first friction disc 7. The pre-charge of the first diaphragm 10 reduces the approach stroke of the stop clutch in order to tighten the friction disc, and always have an effort minimum precharge, for example on the ball bearing of the clutch abutment and on the ball bearing which supports the clutch. This increases the life of said bearings and limits the vibration of the clutch.

The first clutch is of the normally open type. The rest position of the diaphragm thus corresponds to a disengaged state of the clutch device. The diaphragm preferably has a portion of the Belleville washer type for returning the diaphragm to its rest position.

In the rest position of the first diaphragm 10, that is to say when the first stop 13 exerts little or no effort on the first diaphragm 10, the first diaphragm 10 therefore does not exert (or little) on the first pressure plate 5. The first pressure plate 5 is moved away from the reaction plate 6 by means of appropriate return means, such as resilient tongues, so as to release the first friction disc 7.

In a first embodiment shown in figures 1 and 11 the rivets 11 are cylindrical and comprise a head 14 of larger diameter intended to abut against radial fingers 15 of the first diaphragm 10, extending at the radially inner periphery of the latter.

In a second embodiment shown at figure 12 the rivets 11 may have a generally T-shaped head 14 having two radial portions extending opposite the fingers 15 of the first diaphragm 10 so as to serve as a stop. This embodiment makes it possible to limit the radial size of the rivets 11.

The second clutch comprises a second pressure plate 16, and a second friction disc 17 extending radially between the reaction plate 6 and the second pressure plate 16. The same reaction plate 6 is thus used for the two clutches 3 , 4, each friction disc 7, 17 being disposed on the side of one of the two radial faces of the reaction plate 6. The second pressure plate 17 is coupled in rotation to the reaction plate 6 and is movable in translation relative thereto, between an engaged position and a disengaged position, in which it clamps the second friction disk 17 on the reaction plate 6, or respectively releases the second friction disk 17.

The second friction disc 17 is coupled to the second input shaft 2 of the gearbox. Thus, in the engaged position of the second clutch 4, the motor shaft is coupled to the second input shaft 2 of the gearbox.

A second diaphragm 18 is pivotally mounted on the cover 8, by means of rivets 11 '( figure 1 ) ensuring the centering of said diaphragm 18 while allowing it to tilt. The second diaphragm 18 is, as before, in the form of an elastic annular plate bearing on the cover 8 at a bearing zone 19, the second diaphragm 18 thus pivoting around this bearing zone 19 .

The control of the second clutch 4 is conventionally done by means of a second clutch abutment 20 cooperating with the radially inner periphery of the second diaphragm 18, via a force transmission member, not shown. The second diaphragm 18 forms a lever transmitting the force applied by the second clutch abutment 20 to the second pressure plate 16, in order to allow the effective clamping of the second friction disc 17. In particular, the bearing zone of the second diaphragm 18 on the second pressure plate 16 bears the reference 21 to the figure 1 this zone 21 being situated radially between the bearing zone 19 of the diaphragm 18 on the cover 8 and the bearing zone of the second clutch abutment 20 on the second diaphragm 18.

A bearing washer 22, fixed on the cover 8 by means of rivets 23 ( figures 9 and 10 ), comes to press and maintain in position the radially outer periphery of the second diaphragm 18 against the bearing zone 19.

The second clutch 4 is also of the normally open type. In the rest position of the second diaphragm 18, that is to say when the second control stopper 20 exerts little or no effort on the second diaphragm 18, the second diaphragm 18 does not exert (or little) on the second pressure plate 16. The second pressure plate 16 is moved away from the reaction plate 6 by means of appropriate return means, so as to release the second friction disc 17.

The second diaphragm 18, the second pressure plate 16 and the second friction disc 17 are housed in the cover 8. The first friction disc 7 and the first pressure plate 5 are housed in a cover 24 fixed with respect to the cover 8 and the reaction plate 6.

The cover 8 comprises, from the rear towards the front, radial flanges 25 for fixing on the reaction plate 6, connected to an annular portion 26 ( figure 1 ) surrounding the aforementioned elements of the second clutch 4, itself extended by an annular portion 27 extending radially inwardly.

As can be seen in figure 1 , the movable cover 9 has a radially outer portion 28 extending forwardly from the first pressure plate 5 and surrounding the cover 8, extended at the front by a portion 29 extending radially inwards, and even prolonged by a cylindrical flange 30 extending rearward, towards the second diaphragm 18.

As represented in figures 1 and 11 , the free edge 31 of the cylindrical rim 30 defines substantially radial faces capable of serving to support the first diaphragm 10 in order to limit its movement when the first clutch 3 is in the storage position, that is to say before assembly double clutch on the gearbox. Alternatively, the diaphragm can also bear on the heads 14 of the rivets 11.

Once the double clutch is mounted on a vehicle, the first diaphragm 10 bears against the first clutch abutment 13 and the first diaphragm 10 no longer bears on the free edge 31 or on the heads 14 of the rivets 11, in the disengaged position.

In addition, as can be seen in figure 13 , the radially outer portion 28 has radial surfaces 32 facing rearwardly and intended to bear against radial faces 33 facing the front of the reaction plate 6. This makes it possible to limit the displacement of the movable cover 9 in transport phases of the double clutch, before mounting on a gearbox of a vehicle.

In order to compensate for the wear of the first friction disc 7, the first pressure plate 5 and / or the reaction plate 6, the first clutch 3 is equipped with wear-catching means 33.

The structure and operation of these wear compensating means 33 are similar to those of the means described in document FR 2 847 626 , in the name of the Applicant, their positioning being however different.

The wear compensating means 33 comprise a ring 34 mounted around the cylindrical rim 30 of the movable cover 9 and having, radially from the inside to the outside, a radial portion 35, extended by a frustoconical portion 36 flared towards the rearward, itself extended by a substantially cylindrical rim 37 extending forwardly and whose free edge forms ramps 38 extending circumferentially and inclined from the rear to the front. These ramps 38 are particularly visible to figures 2 , 3 , 5 , 7 , 8 and 9 .

The ring 34 is movably mounted in translation and in rotation around the cylindrical rim 30.

Four tabs 39, 40 extend radially outwardly from the rim 37 of the ring 34 ( figure 2 ). Two tabs 39 serve to fix a member 41 in the form of a circular arc, whose outer edge has a toothing 42 extending over only a portion of said outer edge. Two other tabs 40 serve to fix a balancing member 43, also in the form of a circular arc, located diametrically opposite to the toothed member. The circumferential ends of the toothed member 41 and of the balancing member 43 are fixed to the corresponding tabs 39, 40 by means of rivets 44.

The ramps 38 are supported on counter-ramps 45 formed on the rear surface 46 of the radial portion 29 of the movable cover 9 ( figure 9 ).

The rotation of the ring 34 carrying the ramps 38 relative to the movable cover 9 thus causes the displacement of the ring 34 along the cylindrical rim 30 of the movable cover 9.

The movable lid 9 being coupled in rotation with the lid 8 and the reaction plate 6, it is sought to rotate the ring 34 carrying the ramps 38. For this, the toothing 42 of the toothed member 41 meshes with a screw without end 47 mounted in a cassette 48 fixed on the cover 8.

More particularly, the worm 47 is pivotally mounted around a shaft 49 and inside a cassette attached to the outer wall (or front wall) of the radial portion 27 of the cover 8. External wall design , the wall of the lid 8 which is opposed to the internal space housing the second friction disc 17, the second pressure plate 16 and the second diaphragm 18.

As can be seen in particular figures 3 , 4 and 13 , the cassette 48 has a generally U-shaped, the two branches or wings 50, 51 of the U carrying the ends of the shaft 49, the base 52 of the U extending from one wing 50 to the other 51 by surrounding partially the worm 47.

A recess on the top of the cassette 48 ( figure 3 ) allows better holding in centrifugation.

The free ends of said wings 50, 51 carry lateral flanges 53 for fixing on the cover 8. These flanges 50, 51 are fixed to the cover 8 by rivets whose heads 54 extend facing the rear wall of the body 41. As is better Figures 7 and 8 , the cassette 48 further comprises a flange 55 extending radially towards the inside, facing the front face of the toothed member 41. In operation, the toothed element 41 is preloaded on the rim 55.

In the variant of the figure 7 the wings 50, 51 of the cassette 48 comprise surfaces 55 facing the rear face of the toothed element 41.

Said surfaces 55 'and the flange 55 of the cassette 48 form stops limiting the axial displacement or the bending of the toothed element 41 so that the toothing of the latter remains situated at right angles to the axis of the worm 47.

In the variant of the figure 7 it is the heads 54 of the aforementioned rivets and the rim 55 of the cassette which form the abutments limiting the axial displacement or the bending of the toothed member 41.

The shaft 49 further carries a ratchet wheel 56 coupled in rotation with the worm screw 47, for example formed integrally therewith. An elastic member 57 is mounted between the wing 51 and the ratchet wheel 56 so as to press the ratchet wheel 56 and the endless screw 47 against the opposite wing 50. This wing 50 has an internal surface 58 ( figure 3 ), intended to come into contact with the worm 47, which is screwed to increase the hardness and limit its wear by friction. This work hardening can be performed by stamping, knurling, roller burnishing, mechanical polishing or by electrochemical operations, such as electropolishing or electrolytic polishing.

As can be seen in figures 1 and 6 , an opening 59 is formed in the movable cover 9 to allow the mounting of the cassette 48 outside the cover 8, the cassette 48 extending partially through this opening 59.

The ratchet wheel 56 cooperates with a pawl 60 in the form of a metal elastic plate attached to the front face of the radial portion 27 of the cover 8.

The pawl 60 has a radially inner portion extending substantially radially and fixed on the front face of the cover 8, and a radially outer portion forming an angle with the radially inner portion, extending rearwardly through an opening 61 of the lid 8.

The structure of the pawl 60 is similar to that of the pawl described in the document FR 2 847 626 .

In particular, the radially outer portion of the pawl 60 comprises a control tongue 62 ( figures 1 , 6 and 13 ) cooperating with the teeth of the ratchet wheel 56 so as to allow the rotation of the ratchet wheel 56 in a direction of rotation, in case of wear, and to prevent the rotation of the ratchet wheel 56 in the direction of opposite rotation. The radially outer portion of the pawl 60 also comprises a return tongue 63 ( figures 1 and 6 ).

The first diaphragm 10 comprises an external peripheral 64 of pawl actuation 60, intended to bear against the return tab 63 of the pawl 60 in the disengagement phase, and intended to bear against the control tab 62 in phase clutch.

In order not to hinder the movement of the actuating finger 64 and the return tongue 63, the bearing washer 28 has an opening 65 ( figure 1 and 10 ) allowing the passage of said actuating finger 64 and said return tongue 63, upon actuation of the first diaphragm 10 in the disengaging phase.

The radially outer portion of the pawl 60 further comprises two lateral tabs 66 ( figures 3 , 4 and 6 ) forming abutments intended to abut against the lateral edges of the opening 61 of the cover 8 during the actuation of the first diaphragm 10 in the disengaging phase.

The operation of the wear compensating means 33 will now be described. As indicated above, this operation is similar to that of the means of catching up the wear of the document FR 2 847 626 .

It will be assumed first of all that the linings 67 of the first friction disc 7, the first pressure plate 5 and the reaction plate 6 do not are not used. In this case, in the clutching phase, the first diaphragm 10 is displaced by the first clutch abutment 13, so that the outer periphery of the first diaphragm 10 and its actuating finger 64 are displaced forwards. by pushing the control tongue 62. The free end of the control tongue 62 is then pushed into the bottom of a tooth of the ratchet wheel 56.

During disengagement, the outer periphery of the first diaphragm 10 is moved backwards towards its rest position. The actuating finger 64 of the first diaphragm 10 then presses on the return tongue 63 of the pawl 60. Consequently, the return tongue 63 and the control tongue 62 of the pawl 60 are moved backwards, until that the lateral tabs 66 of the pawl 60 abut against the lateral edges of the opening 61 of the cover 8. If no wear has occurred, the removal of the control tongue 62 vis-à-vis the corresponding tooth of the ratchet wheel 56 is not enough to jump the tooth. The ratchet wheel 56 can not therefore be rotated during the next clutching phase and the wear compensating means 33 do not modify the position of the first pressure plate 5 with respect to the reaction plate 6.

If, on the contrary, the first friction disc 7, the first pressure plate 5 and / or the reaction plate 6 are worn, in the clutch phase, the outer periphery of the first diaphragm 10 and the control tongue 62 can be moved forwardly enough to slightly rotate the ratchet wheel 56 about the shaft 49. During this clutch phase, the ring 34 is immobilized in rotation, by wedging between the first diaphragm 10 and the movable cover 9. Thus, the toothed member 41 is also immobilized in position. The rotation of the ratchet wheel 56 and the worm 47 meshing with the toothing 42 of the toothed member 41 then causes the ratchet wheel assembly 56 - worm 47 to slide along the shaft 49. and towards the wing 51, compressing the elastic member 57. Of course, the width of the teeth of the ratchet wheel 56 and the width of the control tongue 62 are such that their cooperation is maintained during this sliding.

In the next disengaging phase, the ring 34 carrying the toothed member 41 is released, the control tab 62 prevents the ratchet wheel 56 and the worm 47 from rotating and the ratchet wheel assembly 56 - screw endless slide 47 slides along the shaft 49 and towards the wing 50, under the action of the elastic return member 57. This causes the rotation of the ring 34 relative to the movable cover 9. The Ramps 38 are thus displaced relative to the counter ramps 45 so as to move away from the ring 34 and the movable cover 9. The distance between the bearing zone 68 of the first diaphragm 10 on the ring 34 and the radial portion 29 of the movable lid 9 is increased, which ultimately has the effect of reducing the distance between the first pressure plate 5 and the reaction plate 6 to compensate for wear.

Several phases of clutch and disengagement may be necessary to make up the entire game generated by wear.

The invention thus proposes a double clutch, one of the clutch mechanisms 3, 4 is equipped with wear compensating means 33, having a reduced axial and radial dimensions. Although the structure and operation of these wear compensating means 33 are similar to those of the document FR 2 847 626 their arrangement at the front of the double clutch makes it possible to increase the compactness of the double clutch while enabling the clutch mechanism 3 to be made up to the rear of the double clutch.

Claims (14)

1. Dual clutch with wear compensation, in particular for a motor vehicle, comprising at least one reaction plate (6) intended to be coupled in rotation to a driving shaft, a first and a second friction disc (7, 17) bearing friction linings (67) and intended to be coupled respectively to a first and a second driven shaft (1, 2), a first and a second pressure plate (5, 16), actuated respectively by a first and a second diaphragm (10, 18) so as to clamp or release the first and the second friction disc (7, 17) onto or from the reaction plate (6), the first pressure plate (5) being fixedly connected to a cover (9) which is translationally movable with respect to the reaction plate (6), and being actuated by the first diaphragm (10) bearing on the movable cover (9), and means (33) for compensating the wear of the first friction disc (7), the first pressure plate (5) and/or the associated reaction plate (6), characterized in that the wear compensation means (33) comprise ramp means (34, 38) arranged on the first diaphragm side and cooperating with counter-ramp means (9, 45) arranged on the movable cover (9) side, the ramp means (34, 38) and the counter-ramp means (9, 45) being arranged between the first diaphragm (10) and the movable cover (9) in such a way that the rotation of the ramp means (34, 38) with respect to the counter-ramp means (9, 45) modifies the distance between the first diaphragm (10) and the movable cover (9), the ramp means (34, 38) bearing a toothing (41, 42) meshing with a worm (47), the wear compensation means (33) additionally comprising means for rotationally driving the worm (47) that are able to be rendered operational as a result of wear when the first diaphragm (10) is actuated, the worm (47) being borne by a part (8) secured to the reaction plate (6) that cooperates with the first pressure plate (5) for clamping the first friction disc (7).
2. Dual clutch according to Claim 1, characterized in that it comprises a single reaction plate (6) arranged axially between the first and second friction discs (7, 17).
3. Dual clutch according to Claim 1 or 2, characterized in that the means for driving the worm comprise a ratchet wheel (56) which rotates as one with the worm (47) and cooperates with a pawl (60) able to be moved during the actuation of the first diaphragm (10).
4. Dual clutch according to one of Claims 1 to 3, characterized in that the second pressure plate (16), the second friction disc (17) and the second diaphragm (18) are housed in a cover (8) fixed to the corresponding reaction plate (6), the worm (47) being mounted rotatably in a cartridge (48) fixed to the cover (8), outside the latter.
5. Dual clutch according to Claims 3 and 4, characterized in that the worm (47) and/or the ratchet wheel (56) are rotatably mounted inside the cartridge (48), the worm (47) and/or the ratchet wheel (56) being pressed by an elastic member (57) against a workhardened face (58) of the cartridge (48).
6. Dual clutch according to Claims 3 and 4, characterized in that the first diaphragm (10) comprises an outer peripheral finger (64) for actuating the pawl (60), the cover (8) bearing a washer (22) for bearing the second diaphragm (18) that comprises an opening (65) allowing the passage of the said actuating finger (64) during the actuation of the first diaphragm (10).
7. Dual clutch according to one of Claims 4 to 6, characterized in that a toothed member (41) meshing with the worm (47) is fixed to the ramp means (34), the bending or the axial movement of the toothed member (41) being limited by two opposed stops (54, 55).
8. Dual clutch according to Claim 7, characterized in that the bending or the axial movement of the toothed member (41) is limited by a rim (55) of the cartridge, on the one hand, and by opposed surfaces (55') formed in two wings (50, 51) of the cartridge (55), on the other hand, the said wings (50, 51) serving as a support for the worm (47).
9. Dual clutch according to Claim 7, characterized in that the bending or the axial movement of the toothed member (41) is limited by a rim (55) of the cartridge, on the one hand, and by the means (54) for fixing the cartridge (48) to the cover (8), on the other hand.
10. Dual clutch according to one of Claims 1 to 9, characterized in that the first diaphragm (10) is tiltably mounted on the cover (8) by way of rivets (11), the tilting of the first diaphragm (10) being limited by the heads (14) of the said rivets (11) before mounting on the vehicle and, in the other direction, by a substantially radial face (31) of the movable cover (9).
11. Dual clutch according to Claim 10, characterized in that the heads (14) of the rivets (11) serving as a stop for the first diaphragm (10) have the general shape of a T whose lateral branches are intended to bear against radially inner fingers (15) of the first diaphragm (10).
12. Dual clutch according to one of Claims 1 to 11, characterized in that the ramp means comprise a ring (34) mounted rotatably and translatively about a cylindrical part (30) of the movable cover (9), the ring (34) comprising ramps (38) extending circumferentially and cooperating with complementary counter-ramps (45) formed on the movable cover (9).
13. Dual clutch according to one of Claims 3 to 12, characterized in that the pawl (60) is formed from an elastic lamella having a control tongue (62) cooperating with the teeth of the ratchet wheel (56) so as to allow the rotation of the ratchet wheel (56) in one direction of rotation in the event of wear, and to prevent the rotation of the ratchet wheel (56) in the opposite direction of rotation, the first diaphragm (10) bearing against a return tongue (63) of the pawl (60) so as to move the control tongue (62) during the actuation of the first diaphragm (10).
14. Dual clutch according to Claims 4 and 13, characterized in that the pawl (60) comprises at least one lateral tab (66) forming a stop intended to bear against the cover (8) during the actuation of the first diaphragm (10).

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